Number & the laws of arithmetic
Order of operations
When a calculation has different operations, do multiplication and division first, then addition and subtraction.
The order
1. First: multiplication (×) and division (÷). 2. Then: addition (+) and subtraction (−). Getting the order wrong gives the wrong answer!
Worked examples
With multiplication
- Work out 4 + 9 × 5.
- Do 9 × 5 = 45 first.
- Then 4 + 45 = 49.
Answer: 4 + 9 × 5 = 49
With division
- Work out 16 + 8 ÷ 4.
- Do 8 ÷ 4 = 2 first.
- Then 16 + 2 = 18.
Answer: 16 + 8 ÷ 4 = 18
Where you see this in real life
- Working out a total bill when some items are bought in multiples.
- Programming a calculator or computer, which always follows this order.
- Checking a friend's working to spot an order mistake.
Key words
- Operation
- A maths action: adding, subtracting, multiplying or dividing.
- Order of operations
- The rule to do × and ÷ before + and −.